1. Field of the Invention
The present invention generally relates to an electrical connector assembly, and more particularly to an electrical connector assembly having a pick-up device assembled thereon to provide a vacuum suction pick-up surface.
2. Description of Related Art
Vacuum suction mechanisms are well known in the electronic assembly art and are used for retrieving electronic components, such as electrical connectors, from a supply source and transferring the component by applying negative air pressure to the components and placing the component on a printed circuit board (PCB) in a preselected position for soldering. Generally, the vacuum suction mechanism comprises a suction nozzle. An electrical connector is grasped by the suction nozzle and is robotically transferred to the position on the printed circuit board with great accuracy.
Most electrical connectors, however, are devoid of flat, solid surface suitable for being grasped by the suction nozzle. To overcome this problem, transfer or placement members having a flat, non-porous surface have been developed for attaching to connectors. Such connector placement members are described in the U.S. Pat. Nos. 5,688,133; 4,396,245; 5,249,977; 5,681,174; 6,174,171; and 6,439,901. These patents describe placement members designed for an electrical connector having two opposite sidewalls extending upward from a connector body. The placement members have a flat top surface suitable for being grasped by a vacuum suction nozzle and downwardly extending legs for engaging with the sidewalls of the connector body.
For example, FIGS. 6 and 7 show the placement cover of U.S. Pat. No. 5,688,133 (the '133 patent). The placement cover 8 is made of metallic material, formed by stamping. The placement cover 8 includes a cover plate 80 with a flat top surface and two pairs of resilient legs extend downwardly from each end of the cover plate 80. Each pair of legs has an outer engagement leg 81 and an inner engagement leg 82. The outer and inner legs 81, 82 are spaced apart from each other to define a receiving space 83. The dielectric housing 90 of the connector 9 has a pair of opposing longitudinal sidewalls 901 and a center wall (not labeled). A slot 902 is defined between the sidewalls 901 and the center wall. When the placement cover 8 is assembled on the connector 9, each space 83 receives a sidewall 901 of the dielectric housing 90 and the outer and inner legs 81, 82 abut against the outer and inner surfaces of the sidewalls 901. However, the placement cover 8 of the '133 patent is made of metal and the shape and dimension of the outer and inner engagement legs 81, 82 must be precisely formed so that they can be mated with the connector reliably and therefore, the manufacturing process is complicated and adds cost.
U.S. Pat. No. 6,439,901, which has the same assignee as the present invention, discloses a placement member made of a resilient dielectric material, as shown in FIG. 8. The placement member 7 is assembled on a connector 6 and has a pair of downwardly projecting legs 71 at each end thereof. A retaining foot 710 is formed at an end of each leg 71 for abutting against an inner surface of longitudinal sidewalls 61 of the connector 6. The manufacturing method of the placement member 7 is simpler than that of the placement cover 8. However, the placement member 7/8 has no positioning element and therefore, the placement member 7/8 may end up being positioned in any place along the longitudinal direction “N”. As a result, the placement member 7/8 could not be assembled on true position of the electrical connector, and the precision and efficiency of the robotic assembly is reduced.
However, for right-angle electrical connector widely used in the electronic industry, whose mating face facing to a corresponding connector is perpendicular to a mounting face facing to a printed circuit board, the placement members above-mentioned are not applicable. Most right-angle electrical connectors include a dielectric housing with a flat top surface suitable for being grasped by the suction nozzle. However, the top surface of housing is commonly relatively small and not smooth enough. So if the top surface is used as the placement member, the connector can't be grasped firmly by the vacuum suction, and may wobble or fall off in the process of being transferred to a printed circuit board.
U.S. Pat. No. 6,210,225 (the '225 patent) discloses a right-angle electrical connector with a pick-up cover. The electrical connector comprises an elongate pick-up cover and an elongate insulative housing. An upper surface is disposed on the top of the insulative housing and defines several positioning holes and recesses, each recess further forming a corresponding tab therein. A pair of guiding arms extends rearwardly from a rear side of the insulative housing. The pick-up cover is made of a metal material and comprises a flat plate with an upper side and a lower side, a pair of latches extending downward from the lower side. Several positioning ridges are formed on a forward portion of the lower side and a positioning bar is formed on a rearward portion of the lower side between the latches. A clipping portion is formed at a distal end of the latches. In use, the flat plate of the pick-up cover is fitted to the upper surface of the housing, the clipping portion of the latches of the flat plate sliding from the rear of an outer side of the guiding aims toward the rear side of the housing, the positioning ridges on the lower side snappingly engaging with the positioning holes in the upper surface, the positioning bar engaging with upper inside edges of the guiding arms and the rear side of the housing. The conductive pick-up cover is thus retained on the housing firmly.
Obviously, the manufacture process of the conductive pick-up cover mentioned in the '225 patent is complex and accordingly increases cost of the manufacture. Furthermore, the engagement of the pick-up cover with the connector is so tedious that the efficiency of their engagement is low. Hence, an electrical connector assembly having an improved pick-up device is desired to overcome the above-mentioned disadvantages.